How to delete bone driver fmodifiergenerator
Here is some commented console code using FCurveModifier.remove(...) I have a location.x driver on the context object's pose bone "Bone", which has an fcurve generator modifier.

&gt;&gt;&gt; driver = C.object.animation_data.drivers[0]
# driver 0 is driving location.x of pose bone "Bone"
&gt;&gt;&gt; driver.data_path
'pose.bones["Bone"].location'

&gt;&gt;&gt; driver.array_index
0
# if len(driver.modifiers) or somesuch
&gt;&gt;&gt; mod = driver.modifiers[0]
&gt;&gt;&gt; mod
bpy.data.objects['Armature']...FModifierGenerator
# yep it's a GENERATOR
&gt;&gt;&gt; mod.type
'GENERATOR'
# remove it.
&gt;&gt;&gt; driver.modifiers.remove(mod)